1. Field of the Invention
This invention relates to fuel pressure regulators for use in fuel delivery systems of vehicles, and more particularly to diaphragmed fuel pressure regulators.
2. Description of the Related Art
Fuel pressure regulators for use in fuel delivery systems of vehicles are well known in the art. In a typical fuel delivery system for a vehicle, the fuel delivery system includes a fuel tank, a fuel pump, a fuel filter, a fuel pressure regulator, a fuel return line, and a fuel metering device for supplying the appropriate amount of fuel to the vehicle engine.
The fuel pump, typically electrically operated, constantly draws fuel through an inlet disposed within the fuel tank. The fuel is forced through the pump outlet where it enters a fuel filter/regulator assembly through a fuel supply port. Most of the fuel passes through the fuel filter and out through an outlet port that is connected to a fuel line that leads to a fuel metering device, such as a carburetor or fuel injectors, for supplying fuel to the vehicle engine. Due to the fuel pump constantly pumping fuel into the fuel line at flow rates usually higher than what is required by the engine, a device is required to return excess flow back to the tank to avoid excess pressure buildup. Most modern fuel delivery systems require that the pressure in the fuel metering device remain relatively constant, within certain tolerances. As such, a fuel pressure regulator is required to regulate the pressure in the fuel line. The fuel pressure regulator acts as a pressure release valve by enabling the excess fuel to be returned to the fuel tank, thus relieving the excess pressure in the fuel line. The fuel pressure regulator acts by opening a valve member when the pressure on the upstream side of the regulator exceeds a predetermined pressure level. When the pressure on the upstream side of the regulator returns to the predetermined pressure level, the valve member closes. Thus the fuel pressure regulator acts to keep the pressure in the fuel line relatively constant within certain prescribed tolerances.
Most fuel pressure regulators utilize a diaphragm and valve assembly which act to seal the upstream side of the regulator from the downstream side of the regulator. When the pressure on the upstream side of the diaphragm exceeds a predetermined pressure differential, the diaphragm is caused to deflect thus causing a valve member to open to release fuel through the regulator and out through the return line where it is returned to the fuel tank. Other types of pressure regulators can be used effectively in the present invention and can be considered interchangeable with the particular fuel regulator shown in the drawings.
Prior fuel systems have limitations. For example, when attempting to accelerate quickly the high demand for fuel to the injectors tends to decrease the system fuel pressure because of the typical response of the regulator to such conditions.
In a conventional pressure regular (see FIG. 11), the flow of fuel back to the fuel tank increases as the reference pressure (P) in the fuel line to the engine increases. More flow through the pressure regulator back to the fuel tank means increased fuel line pressure per the typical flow curve (see FIG. 11). So when a large burst of fuel is demanded by the engine upon acceleration, the reference pressure (P) decreases due to the flow to the fuel tank decreasing per the typical flow curve (see FIG. 11). Pressure at the fuel injectors will often drop by 3-5 psi due to the function of a typical pressure regulator. Consequently, there is a need for a fuel pressure regulator which does not have this disadvantage.